This invention relates to a commercial vehicle brake assembly, and more particularly, the invention relates to an anchor pin for supporting the brake shoes of the brake assembly.
Heavy duty brake assemblies typically used on commercial vehicles commonly incorporate a pair of opposing arcuate brake shoes. The brake shoes may be actuated by an actuating member such as an S-cam manipulated by a pneumatic cylinder to force the brake shoes into an engagement with the interior surface of a brake drum. The ends of the brake shoe opposite the S-cam are supported on a brake spider by anchor pins. The pins define pivot points about which the shoes rotate. The anchor pins are received in holes in the spider and extend therefrom to support the brake shoe ends.
As the S-cam manipulates the brake shoes, the brake shoes rotate about the pivot point define by the anchor pin. It is desicreable for the achor pin to rotate with the hole in the spider so that the anchor pin does not bond to the spider as a result of corrosion. That is, it is believed that rotation of the anchor pin within the spider extends the life of the pins and reduces the service to the brake assembly. However, the rotation of the brake shoe about the anchor pin pivot does not always result in the anchor pin rotating within the spider, and the anchor pin frequently corrodes to the spider resulting in increased wear.
Anchor pins are typically designed for the worse case scenario throughout a manufacturer""s brake assembly product line. Prior art brake assembly typically include a cylindrical central portion and a pair of opposing smaller diameter cylindrical end portions extending from either side of the central portion. The central portion is received within the-hole in the spider and the end portions extend beyond the spider to support the brake shoes. The central portion creates a shoulder by which the brake shoe retains the anchor pin within the spider. Since the anchor pins are designed for a worse case scenario, weight and cost is added to the brake assemblies due to the larger than necessary pins and spider. Therefore, what is needed is a smaller anchor pin that rotates within the spider hole in response to manipulation of the brakes shoes.
The present invention provides a brake spider with a hole. An anchor pin is supported within the hole and includes end portions extending from the spider. The end portion has a first interlocking profile, which may be a recess or flat in the outer cylindrical surface of the anchor pin. The cylindrical surface extends preferably to the terminal ends of the pin. That is, the anchor pin has a generally uniform diameter across its length excluding the areas in which the recess or flat is arranged. A brake shoe includes a web having an aperture. The end portion of the anchor pin is at least partially disposed within the aperture. The aperture has a second interlocking profile complimentary to and mating with the first interlocking profile of the anchor pin to prevent relative rotation between the web and the end portion. In this manner, the anchor pin will rotate within the hole of the spider in response to actuation of the brake shoes. Said in another way, the brake shoe and anchor pin will rotate in unison about the pivot point defined by the anchor pin to ensure the pin does not bond to the spider.
Accordingly, the above invention provides a smaller anchor pin that rotates within the spider hole in response to manipulation of the brakes shoes.